The stabilization and controlled delivery of bioactive molecules such as flavors, fragrances, pharmaceuticals or agrochemicals, is an important issue for nearly all applied sciences. Without the stabilization of a concentrated, easily transportable and processible form of the (bio)active agent delivery becomes unreliable and the functional agents will only rarely exhibit their beneficial properties at the predetermined place and time. Indeed, effective encapsulation is required in a wide range of applications, in order to protect sensitive additives from degradation and to control their release and hence optimize their performance according to the requirements of the application. The entrapping of active compounds into a matrix such as micelles, capsules or gels has widely been studied in various branches of industry.
The controlled release of flavors and fragrances, which are highly volatile and can thus only be perceived over a limited period of time, has recently attracted much interest from the flavor and fragrance industry. Active volatile material dispensers, such as air-fresheners, are consumer products commonly used in every day life, and several different types thereof are known. Gels attracted much interest for their potential in the release of flavors and/or fragrances.
Gels, in particular those formed from low molecular weight compounds that respond to pH, are also interesting for biomedical applications.
Non-functionalized guanosines are known to undergo quadruple association into G-quartets through Hoogsten-type hydrogen-bonding forming supramolecular macrocycles which stack into G4-assemblies in the presence of cations such as Na+, K+, and NH4+ with formation of hydrogels (Guschlbauer et al., J. Biomol. Struct. Dyn., 1990, 8, 491-511). The structures are not known to interact with active substances.